Tony Abbott's campaign to form Government has suffered a major blow with Treasury uncovering a shortfall in the Coalition's costings of between 7 and 11 billion dollars. The Coalition is standing by its numbers saying that its budget bottom line will be seven billion dollars better than Labor's over the forward estimates.

Transcript

TONY EASTLEY: There's been a huge blow to Tony Abbott's campaign to form government.

Treasury costings of his election commitments have been released by the Independents who'll decide if he'll become Prime Minister or not, and they show his sums don't add up.

The three country Independents met the head of Treasury, Ken Henry, into the evening and emerged to reveal a shortfall in the Coalition's sums of between 7 and 11 billion dollars.

The Coalition is standing by its costings and says even under the worst case scenario its budget bottom line will be seven billion dollars better than Labor's, over four years.

But it can't escape Treasury's findings of a significant black hole.

From Canberra Samantha Hawley reports.

SAMANTHA HAWLEY: After continual delays the three Independents entered their meeting with the head of Treasury Ken Henry late yesterday afternoon.

When they emerged, late last night Tony Windsor revealed to AM some very bad news for the Coalition.

TONY WINDSOR: Their assessment of the Labor Party promises is about square in terms of what they said and how they've estimated, in terms of the Coalition there is at worst about $11 billion black hole.

SAMANTHA HAWLEY: Treasury's assessment of the Coalition's election policies is damning. The document has now been publicly released by Independents.

It finds over four years the Coalition's policies will improve the budget bottom line by $4.5 billion not the $11.5 billion the Opposition estimated during the campaign.

Treasury finds holes in the costings of a number of policies including in the Coalition's paid parental leave scheme all up the shortfall is between $7 and $11 billion.

Tony Windsor says the Independents will now need an explanation from the Opposition Leader.

TONY WINDSOR: They'll have to be, you know, talking fairly quickly to actually explain some of these things away.

SAMANTHA HAWLEY: Given the hole in the Coalition's costings can you support a Coalition government?

TONY WINDSOR: They haven't pushed me anywhere but I really want to see the Coalition's response to what Treasury have suggested, but it is not a good thing for the Coalition to have these sorts of costings placed, you know, they're enormous numbers.

SAMANTHA HAWLEY: And if the Coalition can't explain the holes in its costings - can you support it?

TONY WINDSOR: Well I think we'll wait and see I'm not going to make decisions on the run.

SAMANTHA HAWLEY: Until this week, Mr Abbott had been resisting submitting all his costing to Treasury.

TONY WINDSOR: We probably understand now why he wasn't interested in releasing the numbers.

SAMANTHA HAWLEY: And there's another problem Tony Abbott needs to deal with too. The incoming Nationals MP Tony Crook says he'll be heading to the cross-bench if he doesn't get a better offer from Mr Abbott for his state of Western Australia before the weeks out.

TONY CROOK: You know we left the ball in his court, you know, he wants to form government and I want to see a fairer deal for Western Australia. Mr Abbott has my phone number.

SAMANTHA HAWLEY: But as it stands if you don't get a call from Tony Abbott if there isn't some bartering, if there isn't something he can offer you, you'll be sitting on the crossbench?